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New oleanonic acid derivatives bearing the pyridine moieties at the positions C(2) and C(28) were synthesized. Heterocyclic moieties were introduced in position C(2) of oleanonic acid by aldol condensation, and in position C(28) by N-acylation. Cytotoxicity of the synthesized compounds was evaluated against 12 tumor cell lines. Aminopyridine-derived oleanonic acid amides with 3- and 4-pyridinylmethylidene group were found to be active against a human prostate cancer cell line PC3 with half maximal inhibitory concentration (IC50) values equal to 1.20 and 2.06 µmol L−1, respectively. [ABSTRACT FROM AUTHOR]

A series of novel azomethine derivatives of benzo-18-crown-6, benzo-15-crown-5, and aniline as well as their complexes with copper(II) acetate have been synthesized. Using the MTT assay, the antitumor activity of the obtained compounds has been determined. The effect of individual structural elements on the antitumor activity of the whole compound has been assessed. [ABSTRACT FROM AUTHOR]

• The antibacterial activity of new synthesized Cu(I) complex were studied. • Topology and molecular docking were performed. • The chemical reactivity was analyzed by NBO, HOMO-LUMO and MEP. • The spectroscopic features of the complex were investigated by DFT. In this article, we synthesized a [CuI(4-pyridinecarboxaldehyde) 4 ] complex characterized by CHN analyses, FT-IR, UV-Vis, and DFT. The spectroscopic characteristics and biological activities of the synthesized complex were investigated using quantum mechanical methods using combined experimental and computational approaches. The orbital NBO and topological AIM approaches were used to investigate intermolecular interactions. According to the second-order perturbation energy analysis, the majority of the E(2) stabilization energies of of LP(N) → LP∗(Cu) are higher than those of LP(I) → LP∗(Cu), implying that the nitrogen atom in the complex is the main contributor to coordination. In addition, the biological activities of the title complex were investigated by using molecular docking analysis. In this investigation, the title Cu (I) complex was the most active molecule, with the maximum antibacterial activity against S. aureus and S. epidermidis infections that should be further clinically investigated due to its effective anti and anti-quorum sensing properties. The title complex showed good antiquorum-sensing activity when tested against C. violaceum ATCC 12472. Furthermore, in-silico molecular docking investigations corroborated the chemical activity correlations. The Cu (I) combination has a maximum dock score for some of the active chemicals. [Display omitted]. [ABSTRACT FROM AUTHOR]

Radioprotective properties of copper complexes with Schiff Bases derived from L-Tyrosine aromatic amino acid and 2-, 3-, or 4-pyridinecarboxaldehydes (Cu.2-Tyr, Cu.3-Tyr, and Cu.4-Tyr) were investigated in rats subcutaneously or orally treated with metallocomplexes at 10 or 40 mg/kg doses 1 or 24 hours before Xray irradiation at 650 R that composes LD50/30 for untreated control irradiated animals. According to the study results, at all the applied schemes of animals preventive treatment Cu.2-Tyr failed to manifest radioprotection. However, Cu.3-Tyr and Cu.4-Tyr demonstrated expressed radioprotective activity that might be mainly related to their respective support of endogenous non-enzymatic antioxidant defence system of the organism. It is concluded that the position of carboxaldehyde group with regard to nitrogen of pyridine ring, viz. 3 or 4, is of great importance for manifestation of radioprotective activity of Schiff Base copper complexes derived from pyridinecarboxaldehydes and L-Tyrosine. [ABSTRACT FROM AUTHOR]

Abstract: Emission and excitation spectra of 3- and 4-pyridinecarboxaldehyde vapors have been measured at different pressures down to 10−2 Torr. The phosphorescence quantum yield measured at low pressure as a function of excitation energy is nearly constant in the range of excitation energy corresponding to the S1(n, π*) state, but it decreases abruptly at the S2(π, π*) threshold. The onset of the abrupt decrease of the yield corresponds to the location of the S2 absorption origin of each molecule, indicating that the nonradiative pathway depends on the type of the excited singlet state to which the molecule is initially excited. The relaxation processes are discussed based on the pressure and excitation-energy dependence of the phosphorescence quantum yield. [Copyright &y& Elsevier]

Photocatalytic oxidation of methylpyridine isomers (2-methylpyridine, 3-methylpyridine, and 4-methylpyridine) was investigated in a mixed solution of acetonitrile and water or acetonitrile using various kinds of TiO2 powders as photocatalysts. The main products from methylpyridine isomers were pyridinecarboxaldehyde isomers (2-pyridinecarboxaldehyde, 3-pyridinecarboxaldehyde, and 4-pyridinecarboxaldehyde). Rutile large TiO2 particles showed the highest level of activity for oxidation of 2-methylpyridine probably because band bending was necessary for the oxidation of 2-methylpyridine. On the other hand, a fine particle having an anatase or rutile phase showed a higher level of activity than large TiO2 particles for oxidation of 3-methylpyridine. A rutile fine particle showed the highest level of activity for the reaction. It was found that pure rutile or pure anatase particles were inactive for oxidation of 4-mathylpyridine. If the particles are not extremely small, pure rutile and pure anatase powders show fairly high levels of activity, and those containing both anatase and rutile phases show the highest level of activity. The activity of pure rutile particles was also enhanced by physically mixing them with a small amount of small anatase particles, which were inactive for this reaction. These results can be explained by the synergism between rutile and anatase particles. All of these reactions effectively proceeded even under anaerobic conditions. Photocatalytic reduction of methylpyridine isomers concomitantly proceeded on TiO2 particles under the conditions used. These results suggest that the activities of TiO2 photocatalysts for oxidation of methylpyridine isomers are dominated by the oxidation potential of alkylpiridine and band bending of TiO2 particles. [ABSTRACT FROM AUTHOR]

Reaction of potassium tetrachloroaurate(III), KAuCl 4 , with 2-pyridinecarboxaldehyde (2CHO-py) have been examined in protic HX (X = OH, OMe, OEt, OCH 2 CH 2 CH 3 , OCH 2 CH 2 CH 2 CH 3 , OCH 2 CF 3 ) solvents. Compounds in which the pyridine ligand is N or N - O coordinated in a newly carbonyl hydrated or in semi- and acetal-forms, derived by addition of one or two hydroxylic molecules, have been isolated; these include dichloro[pyridine-2(α-hydroxymethanolato)]gold(III) ( 1 ), dichloro[pyridine-2(α-ethoxymethanolato)] gold(III) ( 2 ), dichloro[pyridine-2[α-(2,2,2-trifluoroethoxymethanolato)]gold(III) ( 3 ), trichloro(2-pyridinecarboxaldehyde dimethyl acetal)gold(III) ( 4 ), trichloro(2-pyridinecarboxaldehyde diethyl acetal)gold(III) ( 5 ), trichloro(2-pyridinecarboxaldehyde di-1-propyl acetal)gold(III) ( 6 ) and trichloro(2-pyridinecarboxaldehyde di- 1 -butyl acetal)gold(III) ( 7 ). The crystal and molecular structures of ( 2 ), ( 5 ) and ( 7 ) have been determined by X-ray methods. Compound ( 2 ) crystallizes in space group Pna 2 l with Z = 4, a = 7.8914(4), b = 17.3660(4) and c = 8.3873(5) Å; ( 5 ) crystallizes in space group $ P \bar {1} $ with Z = 2, a = 7.7779(3), b = 8.2878(2) and c = 13.3202(6) Å, α = 96.975(2), β = 95.096(2), γ = 115.027(2)°; ( 7 ) crystallizes in space group P 2 1 / a with Z = 4, a = 14.5438(12), b = 8.9865(7) and c = 15.0362(11) Å. [ABSTRACT FROM AUTHOR]

Cu(I) complexes of formula Cu(PPh)LClO [L = 2 or 3 pyridine carboxaldehyde] are synthesised and characterised to explore the coordination of an aldehyde, a hard and neutral oxygen donor to a soft Cu(I) centre. The structural and spectroscopic results illustrate that only in 2-pyridinecarboxaldehyde, the 'C=O' group coordinates to soft Cu(I) centres due to a favourable chelate effect, while in 3-pyridinecarboxaldehyde, it remains uncoordinated. Upon chelation via N and O donors, 2-pyridinecarboxaldehyde resembles bipyridine or phenanthroline in terms of its bite angle and spectroscopic features. Such chelation can be easily challenged with coordinating anions like bromide, or more basic pyridines. A drastic change in the MLCT absorption signals the decomplexation of the 'C=O' group. The observed results point out that the Cu(I) centre can readily exchange the hard 'O' donor for softer ligands. [ABSTRACT FROM AUTHOR]

A series of aminothiazolylcephalosporin derivatives (1a≈1c) having pyridinylethenyl group at C-3 position was prepared starting from phosphonium salt 3 and 2-, 3- or 4-pyridinecarboxaldehyde and the antibacterial activity of these compounds was investigated. Among them, 4-pyridinylethenyl derivative was more active than 2- and 3-pyridinylethenyl derivatives against Staphylococcus aureus and Escherichia coli. [ABSTRACT FROM AUTHOR]